As nouns the difference between grunt and boom
is that
grunt is a short, snorting sound, often to show disapproval, or used as a reply when one is reluctant to speak while
boom is a low-pitched, resonant sound, such as of an explosion.
As verbs the difference between grunt and boom
is that
grunt is frequentative: gruntle while
boom is to make a loud, resonant sound.
As an interjection boom is
used to suggest the sound of an explosion.